Naming(toString) Lambda-Expressions for Debugging purpose

Question

Sometimes it is usefull to name lambdas. Especially when you pass them around as parameter.

A realy simple example is

public class Main {
    publi         


        

Answer 1

Here's an alternative that comes to mind:

static  Predicate nameIt(String name, Predicate pred) {
    return new Predicate() {
        public String toString() { return name; }
        public boolean test(T t) { return pred.test(t); }
    };
}

This seems pretty simple. Although I haven't benchmarked it, it seems like it ought to be pretty fast. It adds a single object and one method call, and it avoids boxing/unboxing overhead.

The drawback is that you have to write a little function like this for every functional interface for which you want to provide named instances.